diff --git a/hw/xfree86/vbe/vbeModes.c b/hw/xfree86/vbe/vbeModes.c
index 40bd985ce..50ac50d2c 100644
--- a/hw/xfree86/vbe/vbeModes.c
+++ b/hw/xfree86/vbe/vbeModes.c
@@ -435,7 +435,7 @@ VBESetModeParameters(ScrnInfoPtr pScrn, vbeInfoPtr pVbe)
  */
 int
 VBEValidateModes(ScrnInfoPtr scrp, DisplayModePtr availModes,
-                 char **modeNames, ClockRangePtr clockRanges,
+                 const char **modeNames, ClockRangePtr clockRanges,
                  int *linePitches, int minPitch, int maxPitch, int pitchInc,
                  int minHeight, int maxHeight, int virtualX, int virtualY,
                  int apertureSize, LookupModeFlags strategy)
diff --git a/hw/xfree86/vbe/vbeModes.h b/hw/xfree86/vbe/vbeModes.h
index affd5b639..ee0257c15 100644
--- a/hw/xfree86/vbe/vbeModes.h
+++ b/hw/xfree86/vbe/vbeModes.h
@@ -82,7 +82,7 @@ extern _X_EXPORT void VBESetModeParameters(ScrnInfoPtr pScrn, vbeInfoPtr pVbe);
  */
 extern _X_EXPORT int VBEValidateModes(ScrnInfoPtr scrp,
                                       DisplayModePtr availModes,
-                                      char **modeNames,
+                                      const char **modeNames,
                                       ClockRangePtr clockRanges,
                                       int *linePitches, int minPitch,
                                       int maxPitch, int pitchInc, int minHeight,